The present invention relates to a dual lens camera and more particularly, to a dual lens camera provided with a long focus lens and a short focus lens which are arranged side by side and selectively used.
There have been known two types of cameras with selectively usable lenses, one of which is characterized by a converter lens which is replaceably put in the optical axis a master lens and the other is so constructed that a long focus lens (hereinafter referred to as a "telephoto lens") and short focus lens (hereinafter referred to as a "wide angle lens") which are arranged side by side are selected by a movable mirror. The present invention is directed to an improvement of the latter type which is characterized by an increased telephoto-effect.
The latter type of dual lens camera disclosed in Japanese Pat. unexamined publication No. 143013/'79 is shown in FIG. 1 by way of example. There is shown a camera provided with a wide angle lens 2 and a telephoto lens 3 which are arranged side by side in a front part of camera housing 1. Behind the lenses 2 and 3 a movable and a fixed mirror 4 and 5 are disposed, respectively, in such a way that the reflective surface of each mirror intersects the optical axis of the respective lens at an angle of 45.degree.. Rearward the movable mirror 4 there are provided in the camera housing a plate 8 with an exposure aperture 8a provided, a shutter member 9, a film 10 and a film pressure plate 12 held on a back cover 11.
In the camera mentioned above, when the telephoto lens 3 is selected to be used, the movable mirror 4 is shifted to a position shown by a solid line so as to organize a photographing optical path for the telephoto lens 3. Thus, the light passed through the telephoto lens 3 changes its direction at right angles by being completely reflected by the fixed mirror 5 to travel toward the movable mirror 4 so as to further change its direction rearwardly by also being completely reflected at right angles thereby. The reflected light will reach the film 10 passing through the exposure aperture 8a defined in the plate 8 and the shutter 9 which is opening. On the other hand, when the wide angle lens is selected to be used, the movable mirror 4 is returned to the position shown by a dotted line to allow the light passed through the wide angle lens 2 to travel straightly up to the film 10 and intercepts the light reflected by the fixed mirror 5.
Although the lenses of aforementioned type of cameras can be selected easily by shifting the movable mirror 4, there is a shortcoming in such cameras that, when the telephoto lens 3 is selected to be used, it is hard to take a picture with sufficiently satisfactory telephoto-effect because of the fact that a long optical path length is not enssured owing to its crank-shaped optical path. To solve the shortcoming, saying in differently, to emphasize telephoto-effect, it is necessary to keep the two lenses 2 and 3 apart as far as possible. This solution, however, makes such cameras bulky and whereas does not satisfy a requirement for miniaturization of camera.